Malaria as a zoonosis

Kim Tae Yun, Shin Hyun-Il, Ku Bora, Lee Sang-Eun, Cho Shin-Hyeong
Division of Vectors and Infectious Diseases, Center for Laboratory Control of Infectious Diseases, KCDC

In humans, malaria is caused by the infection with four Plasmodium species, P. falciparum, P. vivax, P. malariae or P. ovale. These parasites are transmitted in humans by the mosquitoes of genus Anopheles. However, it has long been known that other Plasmodium species originated from non-human primates could infect residents or travelers of the forest.
Plasmodium knowlesi, the malarial parasite of macaque monkeys in Southeast Asia, is the most common zoonotic malaria parasite. The other common zoonotic malaria parasite is P. simium of South America, which infects platyrrhine monkeys. Human infections with these non-human primate malaria parasites appear to be misdiagnosed as P. malariae or P. vivax infections for a long time. These misdiagnoses are mainly due to the morphological similarities between the parasites when observed under microscope. Studies on the lineage of human malarial parasites have shown that they were transferred across species from African apes and monkeys to humans via mosquito vectors.
Collectively, zoonotic malaria, misdiagnosed for a long time, is an important emerging infectious disease. Changes in human habitation and ecology may facilitate the emergence of new human malarial parasites from non-human primates.

Keywords: Zoonotic malaria, Plasmodium knowlesi, Plasmodium simium, Diagnosis